Drill bit and locking means



Oct. 13, 1964 R E. CONOVER DRILL BIT AND LOCKING MEANS Filed May 51, 1962 mwm mmw INVENTOR H ROBERT El 'CONOVER '1 ot 2% {WW ATTORNEYS United States Patent 3,152,654 DRILL BIT AND LOCKING MEANS Robert E. Conover, Canton, Ohio, assignor to The Timken Roller Bearing Company, Canton, Ohio, a corporation of Ohio Filed May 31, 1962, Ser. No. 199,145 6 Claims. (Cl. 175-482) The present invention relates to drill bits of the type in which a plurality of cutting bits are removably retained on the face of the bit holder. The present invention further relates to a novel means for positively locking the bits in the bit holder.

One of the principal objects of the present invention is to provide a drill bit wherein a plurality of insert cutting bits are locked to a bit holder by the engagement of a pin with the bit shanks.

Another object is to provide a cluster bit construction wherein the insert bits are solidly locked in place and resist torque developed during drilling.

Still another object of the present invention is to provide a cluster bit wherein the lock means is protected during drilling and is able to withstand the high vibration developed in drilling.

It is another object of the present invention to provide a drill bit including a bit holder, a plurality of cutting pins, and means for positively retaining the cutting pins in the bit holder.

A further object is to provide a cluster bit having a plurality of smaller cutting bits which define the outer periphery of the cutting area, and a pair of lock pins retaining the cutting bits in sockets in a holder, one of said pins engaging the bit shanks to positively hold the bits in a fixed position in the bit holder during drilling, and the other pin locking the first pin to the holder.

Among the advantages achieved by the present invention are that each individual cutting bit can be rotated on its own axis to obtain a new gauge cutting edge without affecting any other bit in the group. Also, the internal lock means protects the engaged surfaces from erosion during drilling and thus the gauge diameter of the hole is maintained. Usable parts from a damaged bit assembly can be reused in another bit assembly so that all of the parts are used for their full life. This positive connection between the pin shanks and the bit holder retain the bits in the bit holder so that individual cutting pins are not lost during a drilling operation. The solid locking pin resists spalling due to vibration developed during drilling and the smaller pressure pin is not subjected to drilling forces and has a long service life.

These and other objects and advantages will become apparent hereinafter.

The present invention comprises a cluster bit including a plurality of cutting bits positively retained in a bit holder by lock pins which lock the bit shanks nonrotatively to the bit holder. The invention further consists in the parts and combinaions and arrangements of parts hereinafter described and claimed.

In the accompanying drawings which form part of the specification and wherein like symbols refer to like parts wherever they occur:

FIG. 1 is an end elevational view of a bit holder showing four insert cutting bits in the holder;

FIG. 2 is a fragmentary side elevational view of the bit holder shown in FIG. 1 with only two of the insert bits shown for clarity;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2 showing all four of the insert bit shanks in section with the retaining and locking pins in position,

FIG. 4 is a sectional view taken along line 44 of FIG. 3 with the lock and retaining pins shown in elevation;

FIG. 5 is a fragmentary partial sectional view taken along line 5-5 of FIG. 3; and

FIG. 6 is a fragmentary view partly in section of the locking pins in engaged position.

The present invention embodies a drill bit 10 including a bit holder 11 whose shank portion is adapted to engage a drill rod (not shown). The bit holder 11 has a forward face 12 which is provided with a plurality of pockets or sockets 13. Each pocket 13 opens to the bit holder face 12 and has vertical side walls 14 terminating in a base 15. Extending laterally through the bit holder 11 from side to side is a first passageway 16 which engages the inner side walls 14 of the sockets 13. The opening 16 defines a semicircular groove in each pocket side wall 14. A second transverse passage 18 engages the first passage 16 and is vertically positioned with respect thereto so as to intersect the lower edge thereof. Both the passages 18 and 16 pass completely through the holder 11.

Each of the cutting bits 19 comprises a head portion 20 having a cutting face 21 provided with slots 22 wherein cutting inserts 23 are retained. The bit head portion 20 has flattened sides 24 connecting the cutting face 21 and an opposed shoulder 25. As may be seen in FIG. 1, the bit heads 20 do not engage an adjacent bit head 20, but are freely positioned in the holder 11. The flattened sides 24 on adjacent bit heads 20 are nonabutting. A shank portion 26 having a vertical side wall 27 terminating in a small butt end 28 is connected to the head portion 20 at the shoulder 25. The shank portion 26 is provided with four equally spaced milled flats 29 which are aligned with the first passage 16 in the bit holder pocket 13 when the cutting bit 19 is received in the socket 13.

A first solid pin fastening means 30 is inserted into the first bit holder passageway 16 and engages the groove in the pocket side wall 14 and also engages the notch 29 in the insert bit shank 26.

The first locking pin 30 engages one of the notches 29 in all of the bit shanks 26 and securely locks the insert bits 19 to the bit holder 11. Since the notches 29 have a flattened bottom or base 29a, the engagement of the flats 2% with the pin 30 restrains the bits 19 from rotation during drilling.

The solid locking and retaining pin 31) resists the torque developed by the insert bits 19 during drilling, and has long service life, since it also resists the vibration of the bit shanks 26 against the pin 30 during drilling.

The single pin 31) also locks the four insert bits 19 to the holder 11, thus effecting a considerable savings in material and fabrication costs.

Since the engagement of the pin 30 and the bit shanks 26 is internal (within the holder 11), there is no danger of erosion of the engaged metal surfaces during drilling. If the means for preventing rotation during drilling were external, the engaging surfaces would be subjected to possible erosion eifects of drilling.

A second pin or pin retaining means 31 is tightly positioned in the second passage 18 and engages an annular groove 32 provided in the lock pin 30 to lock the pin 30 securely to the bit holder 11 and retain the pin 30 therein.

The retaining pin 31 is preferably a pressure pin which is of variable diameter and is compressed when inserted into the passage 18 and expands against the walls of said passage 18 to lock itself securely to the holder 11. As the retaining pin 31 engages the notch 32 in the lock pin 50, it retains the lock pin 36 securely in the bit holder passage 16.

The main locking pin 30 cannot be removed from the ,bit holder 11 until the pressure pin 31 is withdrawn from its active position in the passage 18. The insert bits 19 cannot be removed from the bit holder sockets 13 as'long as the lock pin 36 is in place in the passage 16.

When one of the insert-bits 19, becomes worn, the pressure pin 31 is removed and the lock pin 34) then can be removed from the holder 11, thus freeing the insert bits 19. When the worn bit 19 is rotated a quarter turn, a new cutter 23 is presented to the gage diameter of the cutting face 21. The lock pin 39 then is reengaged with the bit shanks 26, to lock the bits non-rotatively in the holder 11, and the pressure pin 31 is reengaged with the lock pin groove 32 to secure the lock pin 36 to the holder 11.

Fluid passages can be provided in the holder 11 and the insert bits 19 so that fluid or air can be forced into the cutting area to carry the rock chips away from the cutting area.

It is intended that either carbide or all steel bits can be used in the present construction. Either single edge bits, commonly known as chisel bits, or multiple edge bits are suitable for use in the present invention. The outer periphery of the cutting area or cutting face 21is defined by the outermost edges of the cutting inserts 23, and must be greater than the outer periphery of the bit holder 11 to drill a clear hole which will hold the cluster bit 10.

The small cutting bits 19 must be grouped radially in the bit holder 11 rather than in a single or double line. Radially grouped bits provide more speed when drilling because of the better coverage, and increase the life of the bit. The largenumber of cutting. edges provided by the cluster bit construction of the present invention also adds to the life of thebit and to the speed of drilling. The present cluster bitprovides more uniformly smaller chips when drilling, and these chips are more easily moved from the hole than large uneven chips. When the portion of a bit insert that defines the gage diameter of the hole becomes worn, it is not necessary to discard the bit, since it can merely be turned a quarter turn and a new insert is presented to the gage diameter. This is of considerable importance, since it increases the life of the bit at least fourfold, besides giving a more constant gage diameter and a more constant degree of sharpness to the cutting face.

If desired, the bit holder 11 can be made of a special material and heat treated to. stand excessive hammering blows, while the bits 19. can be made from material. suitable for brazing or otherwise attaching the cutting inserts 23.

Normally the. bit shanks 26 are provided with as many notches 29 as there are cutting edges or cutting inserts 23 on the bit head 2t). Thus the number of shank flats 29 corresponds to the number of times that the bit 19 can be turned on its vertical axis to present a new cutting edge to the gage diameter of the hole and thus to renew the outer periphery of the cuttingface 21. The flats 29 normally are vertically aligned with a cutting edge, but need not necessarily be.

This invention is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes of disclosure which do not constitute departures from the spirit and scope of theinvention.

What is claimed is: t

1. A cluster bit comprising a bit holder having a plurality of sockets in the working face thereof, a plurality of insert bits having cutting edges and having shanks positioned in said sockets, said shanks being provided with notches in the periphery thereof, said bit holder having a first transverse passage therein aligned with the insert bit shank notches, said passage engaging each of said sockets, said bit holder having a second transverse passage intersecting said first transverse passage, and being in a plane substantially parallel to the plane of the cutting edges of the insert hits, a first locking pin positioned in said first passage and engaging said insert bit shank notches to restrain all of said insert bits from rotation during drilling, said first locking pin having means for receiving a second lock pin in interlocking engagement, and a second lock pin positioned in said second passage and engaging said first pin to lock said first pin to said bit holder.

2. The cluster bit defined in claim 1 wherein said first locking pin is a solid rod with a notch therein aligned with said second passage and said second lock pin is a compressible pressure pin of variable diameter which is compressed when inserted in the second passage.

3. The cluster bit defined. in claim 1 wherein said bit holder is provided with four equally spaced sockets around the axis of the bit and including four insert bits positioned in said sockets, each of said insert bits having four equally spaced notches around the periphery of the shank thereof.

4. A cluster bit comprising a bit holder having a plurality of sockets in the working face thereof, a plurality of insert bits having shanks positioned in said sockets, said shanks being provided with notches, said bit holder having a first and a second intersecting transverse passage therein, said first passage engaging each of said sockets and being aligned with said shank notches, a locking pin positioned in said first passage and engaging said insert bit shank notches to restrain all of said insert bits from rotation during drilling, said locking pin having engagement means for receiving a second lock pin, said means being aligned with the intersecting second passage, and removable means for retaining the locking pin in its passage, said means being positioned in the second transverse passage in the bit holder and engaging the lockingpin engagement means.

5. The cluster bit defined in claim 4 wherein said bit holder is provided with four equally spaced sockets around the axis of the bit and including four insert bits positioned in said sockets, each of said insert bits-having four equally spaced notches around the periphery of the shank thereof aligned with the first transverse passage in the bit holder and having four cutting inserts which are indexable upon removal of the locking pin and removable means to provide four distinct cutting edges to renew the gage diameter of the bit.

6. A cluster bit comprising a bit holder having four equally spaced pockets around the axis of the bit in the working face thereof, a pair of intersecting transverse passages provided in said holder, said passages being transverse of the pockets, one of said passages intersecting all four of said pockets, four insert bits having substantially straight walled shank portions positioned around the axis of the bit in said pockets, the ends of said shank portions resting on the bases of said pockets, each of saidinsert bits having a cutting head portion extending forwardly of the working face of said holder, said head portions having cutting inserts retained therein, the outer periphery of which defines the gage diameter of said cluster hit, each of said shank portions having a pluralityv of flat bottomed notches therein, said notches being vertically aligned with the intersections of said passage with said pockets, the number of notches on each shank coresponding to the number of cutting inserts in the bit head, a solid lock pin positioned in said passage and engaging a notch on each of said bit shanks to retain said insert bits in said holder sockets and to restrain rotation of said bits during drilling, said solid pin having a notch therein aligned with the intersection of said transverse passages, and an expandable retaining pin in the other of said transverse passages, said retaining pin being compressedin said transverse passage and engaging said lock pin notch.

References Cited in the file of this patent UNITED STATES PATENTS 1,423,713 Des Roches July 25, 1922 3,075,593 Holsing Jan. 29, 1963 FOREIGN PATENTS 1,261,091 France Apr. 4, 1961 

1. A CLUSTER BIT COMPRISING A BIT HOLDER HAVING A PLURALITY OF SOCKETS IN THE WORKING FACE THEREOF, A PLURALITY OF INSERT BITS HAVING CUTTING EDGES AND HAVING SHANKS POSITIONED IN SAID SOCKETS, SAID SHANKS BEING PROVIDED WITH NOTCHES IN THE PERIPHERY THEREOF, SAID BIT HOLDER HAVING A FIRST TRANSVERSE PASSAGE THEREIN ALIGNED WITH THE INSERT BIT SHANK NOTCHES, SAID PASSAGE ENGAGING EACH OF SAID SOCKETS, SAID BIT HOLDER HAVING A SECOND TRANSVERSE PASSAGE INTERSECTING SAID FIRST TRANSVERSE PASSAGE, AND BEING IN A PLANE SUBSTANTIALLY PARALLEL TO THE PLANE OF THE CUTTING EDGES OF THE INSERT BITS, A FIRST LOCKING PIN POSITIONED IN SAID FIRST PASSAGE AND ENGAGING SAID INSERT BIT SHANK NOTCHES TO RESTRAIN ALL OF SAID INSERT BITS FROM ROTATION DURING DRILLING, SAID FIRST LOCKING PIN HAVING MEANS FOR RECEIVING A SECOND LOCK PIN IN INTERLOCKING ENGAGEMENT, AND A SECOND LOCK PIN POSITIONED IN SAID SECOND PASSAGE AND ENGAGING SAID FIRST PIN TO LOCK SAID FIRST PIN TO SAID BIT HOLDER. 